Types of Power in AC Circuits

• Active Power (P):
  • Also called real or true power.
  • Represents the actual power consumed or utilized in a circuit.
  • Measured in watts (W).
  • Formula: P = V × I × cos(φ).
• Reactive Power (Q):
  • Represents power stored and released by inductors or capacitors in the circuit.
  • Measured in reactive volt-amperes (VAR).
  • Formula: Q = V × I × sin(φ).
• Apparent Power (S):
  • The total power supplied to the circuit.
  • Measured in volt-amperes (VA).
  • Formula: S = V × I.

Power Factor

Defined as the ratio of active power to apparent power:

Power Factor (PF) = cos(φ)

• Key Points:
  • PF = 1: Ideal case, where all power is utilized.
  • PF < 1: Indicates inefficiencies due to reactive components.

Calculating Power in AC Circuits

Example Problem:

• Voltage (V) = 230 V
• Current (I) = 10 A
• Phase Angle (φ) = 30°

Solutions:

1. Active Power:

   P = V × I × cos(φ) = 230 × 10 × cos(30°) = 1990 W

2. Reactive Power:

   Q = V × I × sin(φ) = 230 × 10 × sin(30°) = 1150 VAR

3. Apparent Power:

   S = V × I = 230 × 10 = 2300 VA

Power Factor Improvement

Improving power factor reduces energy losses and enhances efficiency. Methods include:

• Capacitor Banks: Install capacitors in parallel to the load to compensate for lagging current due to inductive loads.
• Synchronous Condensers: Machines designed to improve the power factor in large systems.
• Power Factor Correction Devices: Automatic systems used in industrial setups.

Applications

• Single-phase AC circuits are used in:
  • Residential power systems.
  • Small-scale industries.
  • Lighting, heating, and cooling systems.

Conclusion

Active, reactive, and apparent power are fundamental in AC systems. Power factor indicates efficiency and can be improved using capacitors or other devices. Single-phase AC circuits are vital in domestic and commercial applications.